Fluidized bed reactors are used in polymerization processes involving reactants and/or catalysts in liquid, gas and solid phases. By blowing a fluid or gas reactant into solid particles from below the particles, a fluidized bed is created which floats on the upwards flowing fluid against gravity. When the fluid flow is ceased, the solid particles will come to a rest at the bottom of the fluidized reactor vessel. In order to avoid inlet pluggage or clogging of the reactor vessel, a fluid distribution plate is introduced which allows the fluid to disperse and pass through towards an upper part of the reactor vessel to create the fluidized bed, but which captures the solid particles with fluid distribution caps when the fluidized bed is settled with the reactor shut off and prevents them from contaminating and clogging the reactor inlet.
The fluid distribution plate has fluid vent holes to allow the fluid to pass through to the upper part of the reactor vessel and evenly distribute the fluid across the fluidized bed. The fluid vent holes are covered by a fluid distribution cap to contain the solid particles above the fluid distribution plate, which avoid reactor inlet pluggage which would require a shutdown to remove the clog.
The fluid vent holes and fluid distribution caps cause a pressure drop over the fluid distribution plate, which pressure drop is preferably as low as possible while maintaining even distribution across and above the plate. The reactor and thus the fluid distribution plate should be designed to permit operation for long periods of time without having to shut down for cleaning.
A problem that may occur in known fluidized bed reactors is the flow resistance and stagnant zones of the fluid vent holes in combination with the fluid distribution caps. The design of the fluid vent holes and fluid distribution caps should provide adequate movement of solids between the holes in the distribution plate to prevent sintering of resin in this area, however in stagnant zones underneath or in the vicinity of the distribution caps resins or solids that are entrained in the recycle fluid may be captured by the distribution cap openings which would accumulate and eventually plug the fluid vent holes, requiring undesired maintenance of the fluid bed reactor.